2007 Technical Summaries
Putting Research into Practice: Implementing a Fatigue Detail Classification Scheme for Mn/DOT’s Steel Bridges
This project implements research that classifies steel bridges based on the frequency and severity of fracture and fatigue-sensitive details that are present in each bridge. The gross ranking of bridges with high, medium or low need for preventive maintenance or special inspection will be stored in Pontis, Mn/DOT’s bridge management database, for use by bridge inspectors and those responsible for managing Minnesota’s bridges.
“This conceptually simple idea—gathering and classifying data from bridge plans and inspection records—means that important information will be readily available to help Mn/DOT manage its steel bridge inventory.”
– Jim Pierce, Mn/DOT Bridge Management Engineer
Improving Minneapolis/St. Paul’s Ramp Metering System for Smoother Traffic Flow
To streamline traffic flow and reduce backups on Twin Cities highways, Mn/DOT engineers researched ways to improve the algorithm they use to estimate queue size on entrance ramps and calculate minimum rates for releasing cars from ramps to highways. More than 20 parameters were tested through computer simulations. The new optimized algorithm and ramp-monitoring system increases average speed and reduces travel time and energy consumption.
“Making improvements to the ramp metering system on Twin Cities freeways will reduce travel time, save fuel and improve safety on the mainline while maintaining acceptable delays at the ramp.”
– Todd Kramascz, Operations Supervisor, Mn/DOT Regional Transportation Management Center
Pavement Testing Software
Developing a Computer Program to Select Peak Dynamic Sensor Responses from Pavement Testing
In order to better analyze the vast amounts of pavement response data that Mn/DOT collects, investigators updated and enhanced Mn/DOT’s Peak-Pick software program. The updated version is more robust and efficient, and provides multiple ways to analyze the data.
“With the new program, you open it up, select as many data files as you want, press ‘go,’ and it’s off. The new version is faster, more efficient and has made great strides in reducing noise in the data, providing more accurate results.”
– Tom Burnham, MnROAD Senior Road Research Engineer
Shear Capacity of Prestressed Concrete Bridge Girders
Design specifications of shear reinforcement requirements in prestressed concrete bridges have changed significantly. Researchers load-tested to failure a girder that was built to older design codes and evaluated its shear capacity. They also examined how to judge the shear capacity of other bridges designed to older specifications.
“The design requirements have changed to include much more shear reinforcement. We want to make good decisions about the safe operating load of these older bridges.”
– Yihong Gao, Bridge Designer, Mn/DOT Office of Bridges
Performance Assessment of Underground Stormwater Treatment Devices
Researchers developed a universal method for evaluating the performance of underground stormwater treatment devices in retaining sediment for removal after a storm event. The method was the first of its kind and was endorsed by ASTM.
“This research developed standardized testing procedures that can be effectively used in evaluating underground stormwater treatment systems directly and effectively.”
– Sue McDermott, City Engineer, Avondale, Arizona; Former Public Works Director, City of Mendota Heights
Development of a PC-Based Eight-Channel Weigh-in-Motion System
Researchers developed technology for a WIM system that can be easily built, can record vehicle weight across four lanes of traffic and does not need to use actual vehicles to calibrate. The system is much less expensive and easier to modify than a proprietary system.
“We’ve proven that you can create a user-friendly and accurate WIM system for a much lower cost than buying a proprietary system. Mn/DOT stands to save a lot of time and money by implementing this system.”
- Alan Rindels, Senior Engineer, Minnesota Department of Transportation
Intelligent Transportation Systems
Using Intelligent Transportation Systems Data to Improve Transit Performance and Management
Researchers analyzed the data collected by automatic vehicle location and automatic passenger counter systems on a Metro Transit bus route to understand and address its service reliability issues, developing a study methodology that can be applied to improve additional routes.
“The methodology developed in this project has the potential to allow transit agencies to use today’s data to improve tomorrow’s service. We hope this research can be applied to commercial software to give agencies more immediate feedback.”
–Sarah Brodt Lenz, Program Administrator, Mn/DOT Office of Transit
Asphalt Pavement Cracking
Investigation of Low-Temperature Cracking in Asphalt Pavements
In the cold climates of the northern United States, asphalt pavements are susceptible to low-temperature cracking. This study identified simple laboratory tests for predicting the fracture resistance of asphalt mixtures, procedures that were found to correspond to field performance.
“This was an excellent start to developing ways to predict and combat low-temperature cracking. The fracture toughness test gave us good results that matched pavement performance.”
– Benjamin Worel, Operations Engineer, Mn/DOT
Surveying Noxious Weeds in Roadway Rights-of-Way
Mn/DOT District 4 staff used a new sampling procedure to locate and measure infestations of noxious weeds and concluded that examining a greater number of much smaller areas, selected with regard to ecozone, was more accurate and would allow for better targeting of weed control resources.
“We can now walk 225 feet instead of a quarter mile to collect the data we need to determine the extent of our weed problem, which herbicides to use, and how to distribute them for the most effective treatment.”
– Tina Markeson, Mn/DOT Senior Natural Resource Forestry Specialist
Toward Zero Deaths (TZD)
Rural and Urban Safety Cultures: Human-Centered Interventions Toward Zero Deaths in Rural Minnesota
To help Mn/DOT shape safety interventions, rural and urban respondents answered survey questions about driving risks and behaviors. A small group then underwent driver testing in simulated urban and rural environments. Rural drivers were found to have lower perceptions of driving risk, and the rural environment appears to encourage unsafe speed choices and intersection crossing behavior, particularly among teen drivers.
“Too many fatalities are happening on rural two-lane highways. Is that because rural drivers don’t drive as well as others? This study showed that that was not the case.”
– Mike Wagner, Highway Engineer, Nicollet County
Roadway Test Section Database
Minnesota's Transportation Research Site Database
During a five-year project, researchers created and populated a database of the many roadway test sections created for research projects across Minnesota over the last several decades. This maximizes test section investments by putting original test data as well as more recent observations of test sites within the reach of city, county and state engineers.
“To gain acceptance with city and county engineers, the database has to be simple to navigate and needs to be publicized regularly. If they start using it for research, they’ll see it’s also available for them to enter in their own test sections.”
– Lou Tasa, Mn/DOT District State Aid Engineer
Biological Control of Canada Thistle
Researchers investigated the effectiveness of the recently discovered biological control agent PST for the control of Canada thistle in roadside rights-of-way and prairie wetland restoration systems, and found that an integrated management system based on PST has a significant impact on the management of this weed.
“Although we did not find the silver bullet, this study is a valuable stepping stone to future efforts to use PST as a cost-effective and environmentally friendly way to manage Canada thistle.”
– Paul Walvatne, Mn/DOT Roadside Vegetation Management Unit Supervisor
Winter Road Maintenance
Using Real-Time Road Condition Measurements for Automated Winter Road Maintenance
Researchers developed and tested a first-of-its-kind measurement system that, when mounted on snowplows, produces real-time measurements of the tire-road friction coefficient. These measurements are used to automatically adjust the application of deicing chemicals, which allows deicing materials to be used more efficiently and reduces environmental damage from chemical runoff.
“The best part about this technology is that we can reduce the amount of salt and chemicals that are applied to roadways during the winter without compromising safety.”
– Rajesh Rajamani, Professor, University of Minnesota Department of Mechanical Engineering
Can Cone Penetration Testing Measure the Resilient Modulus of Soils?
Researchers evaluated the feasibility of using Cone Penetration Testing data to estimate resilient modulus in the field and to identify organic soils. Results show that while the statistical analysis model used by researchers was not sufficient to evaluate resilient modulus or organic soil content, this study provides groundwork for enhancing this model to further the use of CPT in the field.
“This report did not establish a link between resilient modulus and CPT test results. Many problems must still be overcome before CPT measurements can aid pavement design.”
– Bruce A. Chadbourn, Mn/DOT Assistant Pavement Design Engineer
Aggregate Base Materials
Measuring the Material Properties of Aggregate Base Containing Recycled Materials
Researchers performed both field and laboratory measurements of resilient modulus for three reconstructed roads that used recycled asphalt paving material in the pavement base, and also performed modulus, shear strength and deformation tests on reclaimed aggregate base and recycled asphalt mixed at various ratios. This established procedures and generated necessary inputs for Mn/DOT’s pavement design manual.
“We needed to know how recycled material compared with virgin material, and we can now look at the relative stiffness values between the two.”
– Shongtao Dai, MnROAD Research Operations Engineer
Incorporation of Fatigue Detail Classification of Steel Bridges into the Mn/DOT Database
This project produced a framework for enumerating and ranking bridge details that are prone to fracture and fatigue. Such a ranking system will assist in targeting funds and resources to the most vulnerable bridges and in evaluating requests for load limit increases.
“The districts are handling maintenance and inspections well. This ranking tool provides more information to us in the bridge office, helping us start with what’s important in considering safety, inspections and load-increase requests.”
– Jim Pierce, Mn/DOT Bridge Management Engineer
Commuter Bicyclist Behavior and Facility Disruption
Researchers tracked bicycle commuters’ behavior using small Global Positioning System receivers enhanced by a wide-area augmentation system to better understand how infrastructure improvements and disruptions impact cyclists. Small GPS units offer an accurate and affordable method for tracking commuter behavior and will provide transportation planners with data to help prioritize infrastructure improvements.
“The methodology is probably the most important outcome here: It proved that using GPS units to track bicycle commuter behavior can work. We also learned how to make it work better in the future.”
– Darryl Anderson, State Bicycle and Pedestrian Coordinator, Mn/DOT Office of Transit
Repair or Replace Concrete Bridge Decks?
Methods to Select the Lowest Cost Alternative
Researchers performed an economic analysis to identify the most cost-effective maintenance strategies for a large group of aging concrete bridge decks. Based on current prices, researchers determined that repair is preferable to redecking if repair can elevate a deteriorated deck to an acceptable condition. Researchers also developed least-cost repair/replacement strategies for all of the decks in the group.
“This study provides helpful information to fall back on when we’re deliberating about using a particular maintenance action.”
– Paul Kivisto, Mn/DOT Metropolitan Region Bridge Engineer
Demonstration of Ash Utilization in Low Volume Roads
Coal fly ash was used to stabilize reclaimed pavement materials in two Minnesota construction projects to demonstrate the viability of this practice. The ash-treated materials displayed improved stiffness, and analysis of leached moisture did not reveal unsafe trace element levels.
“Fly ash is particularly useful for city and county roads that have lower traffic volumes, since agencies need to use locally available materials and keep costs down.”
– John Siekmeier, Mn/DOT Senior Research Engineer
Pavement Design Using Unsaturated Soil Technology
A new method of using the principles of unsaturated soil mechanics during pavement design was developed. This will allow pavement engineers to better take into account field conditions and seasonal variations in moisture content. The new models developed in this study allow pavement designers to estimate the stiffness and strength of any soil encountered in the field.
“The constitutive models help us understand the effects of moisture we see during field tests. This allows us to be more confident that our pavement performance estimates are reasonable, and we can now better quantify the effects of moisture during construction quality assurance.”
– John Siekmeier, Mn/DOT Senior Research Engineer
Intelligent Compaction (IC)
Field Validation of Intelligent Compaction
Researchers evaluated intelligent compaction monitoring technology used in earthwork construction for quality control and assurance. They found that while IC technology is a feasible alternative for quality control and potentially quality acceptance, some challenges remain in validating IC rollers to accurately interpret their measurements.
“This project provides the foundation for current efforts to implement intelligent compaction and light weight deflectometers in Minnesota.”
– John Siekmeier, Mn/DOT Senior Research Engineer
Concrete Pavement Evaluation
Implementing the International Roughness Index for Concrete Pavement Evaluation
Mn/DOT was trying to improve its method for awarding bonuses to contractors for especially smooth concrete pavement. Investigators compared the old method for measuring smoothness to the new International Roughness Index standard, looking at how each pavement analysis method depicts various surface imperfections and evaluating the different options for implementing IRI incentives.
“Highway 59 in Morris, for instance, exhibited ‘chatter phenomena’ due to a basic wave form in the pavement surface, but it had passed incentives under the PI metric. Because of this, we knew we needed to change the incentive specification to an IRI metric.”
– Bernard Izevbekhai, Principal Research Operations Engineer, Mn/DOT
Improving the Strength and Stability of Prestressed Concrete Through-Girder Pedestrian Bridges
Because of a growing concern about the overall safety of pedestrian bridges, investigators used laboratory studies and computer simulation to gauge their ductility, strength and stability as compared with AASHTO specifications. Results showed that several modifications to AASHTO bridge specifications will make future pedestrian bridges stronger and more resistant to collapse.
“This was a very valuable study on a topic that has seen very little research. The design changes will improve the strength and flexibility of prestressed concrete through-girder pedestrian bridges built in Minnesota.”
– Jihshya Lin, Mn/DOT Bridge Design Unit Leader
Pedestrian and Bicycle Safety
The Safety of Pedestrian and Bicycle Travel in Minnesota: Inventory, Analysis and Prospectus
Researchers scanned the available sources of accident data involving bicycles and pedestrians for trends such as correlations between accidents and neighborhood attributes. They examined current accident data collection and made recommendations to increase the quantity, quality and use of bicycle and pedestrian crash data.
“This project brought together the leaders of many Minnesota organizations around the idea that we need to pay more attention to bicycle and pedestrian safety.”
– Darryl Anderson, Mn/DOT State Bicycle and Pedestrian Coordinator
Left-Turn Signal Safety
Measuring the Safety Effects of Signal Installation and Left-Turn Phasing Schemes
Researchers analyzed before-and-after crash data, and used statistical analysis and computer modeling to measure the safety effectiveness of Mn/DOT’s practices for signal installations and left-turn signal phasing schemes at highway intersections. The research findings were roughly consistent with Mn/DOT’s guidance and practice in these areas; analysis should be repeated in several years when more after-treatment data are available.
“For those situations where we had sufficient data, our findings were basically consistent with Mn/DOT’s current guidelines for the use of protected left-turn phasing on higher-speed highways.”
– Gary Davis, Professor, University of Minnesota Department of Civil Engineering
Factors Affecting Commute Times in the 1990s
The average length of time it took Minnesota workers to commute to work increased about 2.5 minutes during the 1990s, a larger-than-normal increase. Unidentified factors other than urban sprawl and traffic congestion were thought to be creating a significant shift in commuter behavior. A detailed statistical analysis showed little correlation between economic factors and commute times, and that some of the increase was due to a change in methodology in the 2000 census.
“This valuable research into statewide commuting patterns will help us with general transportation planning in the future.”
– Deanna Belden, Economic Policy Analyst, Mn/DOT Office of Investment Management
Crash Mapping Analysis Software
Putting Research into Practice: Updating Minnesota’s Crash Mapping Analysis Tool
The Minnesota Crash Mapping Analysis Tool is a geographic information system-based mapping tool used by Minnesota city and county engineers and other traffic safety professionals to analyze crash data and produce maps, charts and reports of selected crash data. The objective of this project was to augment MnCMAT with current and additional historical crash data, and implement a series of updates that enhance the user interface to better meet user needs.
“MnCMAT is very easy to use. Within a few hours, a user can confidently enter queries and generate reports.”
– Mark Vizecky, Traffic Safety Support Engineer, Mn/DOT State Aid Division
Putting Research into Practice: Training Module for Designing and Constructing with Geosynthetics
A geosynthetics expert leveraged decades of Mn/DOT research and federal guidance to create a one-day seminar that described the range of geosynthetics applications occurring throughout Minnesota, such as pavement reinforcement and pavement layer separation, and presented guidelines for materials, design, installation and inspection for each use.
“There are so many ways to use geosynthetics. We wanted to provide a resource to explain where and how it has been used to help city and county engineers determine the proper materials and installation techniques for their particular need.”
– Lou Tasa, Mn/DOT District State Aid Engineer
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